Singeing is a process which is done to burn off surface fibres from the fabric to produce smoothness. This is done by passing the fabric over brushes to raise the fibres and then passing it over a plate heated by gas flames.
The process by which starch portion of sizing recipe (90 to 95%) is removed is known as desizing. Before yarn is woven into fabric, the warped yarns are coated with sizing chemicals such as starch, binder and softener in sizing paste. This is done to impart strength required for weaving on looms. Sizing is essential for weaving but is an obstacle for dyeing and printing.
Therefore desizing is done in which ‘size’ (mainly starch) is removed from fabric for good dyeing, printing and finishing.
- DESIZING COST
- 0.15 to 0.20 Rs/ meter (For 44” fabric width – 92X88)
- Paste cost – 1 to 2 Rs/ kg
MODERN TECHNOLOGY: Neutral pH desizing by using Enzyme
Scouring, is a chemical washing process carried out on cotton fabric to remove natural wax and non-fibrous impurities from the fibres and any added soiling or dirt. It is a micro cleaning process where softeners, oils, wax, gums and dirt which are commonly found in cotton and rayon fibres are removed to produce a hydrophilic (absorbent) fabric which provides a better adhesion for dyes.
Bleaching is the 3rd step of fabric pre-treatment. It is a process which improves fabric whiteness by removing natural coloration and remaining trace impurities from the cotton.
Bleaching can be avoided if the fabric is dyed with medium to deep shades printed with 100% coverage designs.
MODERN TECHNOLOGY: low caustic/ caustic free scouring using enzyme.
- BLEACHING COST
- Paste Cost Rs./ Kg : 4
- Processing Cost Rs./ Meter : 50 to 55 paisa
Mercerization is a process in which fabrics (typically cotton) are treated with a caustic (NaOH) solution to cause swelling of the fibres. This improves properties such as fiber strength, shrinkage resistance, luster, and dye affinity. The caustic actually rearranges the cellulose molecules in the fiber to produce these changes.
- MERCERIZATION COST
- Processing Cost 0.70 Rs/ meter